18650 in 5v Box Style Mod?

[[amp]]

Are there any issues with using two 18650s instead of the normal 14500s with a 3a/5v regulator? I want to make a beefier 5v box mod, I figure I should get a couple days out of the 18650s since they have a much higher mAh rating.

[Robert T]

No problem, longer run time, I don't really like 14500's but I've never had any AW's. You might get less voltage drop so if you like what you're getting with the 14500's it might be a little hotter. Go for it.

[slimest]

Only weight and dimensions

[[amp]]

Thanks for conformation, I didn't think it would be a problem but just wanted to check before I started ordering stuff. Im kind of going for a big mod so the extras weight & size isn't really an issue for me. I'm going to be building it in a 1290NS enclosure, unless I can jam it all in a 1090NS.

[Topper]

I'm looking also for housing with place bout two 18650 and step-down controler (maybe and digital display) - from where you plan to order ?

[[amp]]

Im going to get my box from pedalpartsplus They have a ton of different enclosures and will powder coat them just about any color you could want. They're normally for making guitar effect boxes but I figured they would work well for a PV mod too. The only drawback I can see is the 4 screws on the back which will make battery swaps a little more of a pain in the ..... I actually just ordered my "prototype" box from them for a 14500 5v box, I'll use this to see if I get the 18650 battery holder to even fit inside the smaller 1090NS case.

[UncleKevin]

I had the same question after reading this warning at :
http://www.batteryjunction.com/wf139-18500-combo.html

"These fully protected cells simplify usage with their integrated PCB. Perfect for your single cell application these cells are not for pack building and should not be welded or soldered on which may defeat pr daamage the PCB protection. If you are building a pack please choose one of our other cells and the appropriate PCB."

Note this combo kit is for 18500's but I have seen similar warnings for 18650's.

Does wiring 2 18500's in parallel (using a battery holder) constitute a pack?

What exactly is the concern here? Can anyone point to some reference that explains the problem?

I have noticed that a number of mods isolate the batteries from everything else. Is that done because of heat? Safety? Some other reason?

Thanks for the pointers!

[gwhy!]

I had the same question after reading this warning at :
COMBO: Ultrafire WF-139 Lithium Ion Charger / 2 Ultrafire 18500 1600mah 3.7v Batteries

"These fully protected cells simplify usage with their integrated PCB. Perfect for your single cell application these cells are not for pack building and should not be welded or soldered on which may defeat pr daamage the PCB protection. If you are building a pack please choose one of our other cells and the appropriate PCB."

Note this combo kit is for 18500's but I have seen similar warnings for 18650's.

Does wiring 2 18500's in parallel (using a battery holder) constitute a pack?

What exactly is the concern here? Can anyone point to some reference that explains the problem?

I have noticed that a number of mods isolate the batteries from everything else. Is that done because of heat? Safety? Some other reason?

Thanks for the pointers!

2 or more cells in parallel becomes a pack, Im not a expert on these cells but if they have built in protection then the fact that you parallel them can fool the protection to think that one is still at a save voltage, even though the cell may be below the safe point of around 2.9v ( i think ), if this is the reason then I can see why It could be a problem. If the cell voltage drops to below this save discharge voltage then the cell can become unstable and you may have thermal runaway when you recharge the cell. A cell that goes into thermal runaway can explode.